Ioan Rodean

On-line monitoring of OHL conductor temperature; live-line installation

This paper shows the Live working technology to install the On-line Monitoring system on Overhead lines. The Monitoring System, which is based on the contact-free SAW-technique, is introduced. During periods of high ambient temperatures, low wind speed and high electrical system load conditions, monitoring and analyzing regional areas of the transmission network can be essential to evaluate the conductor operating temperature. The temperature of the conductor at the point of installation can be measured and the data transmitted wirelessly to a data collection point.

Criteria for applying of Live Working Technologies in Romanian Transmission Power Grid

This paper presents the conditions that must be met in terms of technical and organizational for implementation of modern technologies. It also shows how to perform maintenance of electrical installations in the Transmission Power Grid by applying these technologies. Technical requirements, imposed by the beneficiary, refers to: the application of technology in the operating conditions at that time slot for grid or area of power network, dam and losses that may occur, technical level and wear allowed for components of equipment, technical conditions to be met spare parts, technical measures that are taken for the safety of the power system or the area power grid, technical measures for occupational health and safety to be taken, environmental conditions. Organizational requirements, that can only be achieved through close cooperation between customer and contractor, refers to: measures to be taken to prepare technical measures for works and operating schemes for achieve power grid or grid area, conditions for quality tasks and assurance organization of the project, taking measures to reduce the risk to work, preparing and providing equipment technologies, information on the project, professional training. New methods are choosing for performing maintenance with modern technologies which regarding both aspects logical and algorithms.

Live rehabilitation of 400kV OHL Mintia-Sibiu

The 400kV Mintia-Sibiu OHL was build in 1971-1972. In 2011-2013 National Transmission Company (CN Transelectrica SA) performed a refurbishment project for the OHL elements. A part of this large project is executed in LW technology by the maintenance subsidiary of Transelectrica (SC Smart SA). The live working part of project consist of: replacement of suspension insulation strings, replacement of insulation chain elements, replacement of dampers, replacement of vibration dampers, Installation of armour-rods together with suspension clamps, painting, Installation of aerial plates on towers, replacement of damaged tower elements. The work was done using some new methods for access on the conductors, including the aerial insulating platform class A. When a project starts we should consider all the ways to complete the works. Considering present technologies used in Romania some works needs deenergization of the line. For other parts of the project Live Working is mandatory, in order to maintain the systems stability. At the end of the project an economical analysis is done. Was it efficient to use Live Maintenance technologies?

Live operating and efficiency of equipment's management

The paper present the methods used in recent years in the national power grid to operate more efficiently as high voltage equipment. It includes shares of minor maintenance and operation undertaken by our company for management installations. It also briefly describes the results of applying new technologies and the technical analysis performed using such technical data. As part of asset management technologies have been applied without withdrawal from service of installations, allowing transmission of electricity at full capacity. In applied technologies for minor maintenance remember inspections multispectral spectra in visual, infrared, ultraviolet and laser and live working technologies. Within the operation of equipment were used more management applications databases, which were subsequently used in technical analysis. Also in the operation were used methods of online analysis for operational behavior of equipment. It presents the results of a comparative analysis of the costs of the technologies for minor and corrective maintenance without redraw from service of equipment and exploitation of modern equipment versus traditional technologies Some conclusions are presented at the end, much like their own recommendations for more efficient operating of equipment.

Live working methods for anchors replacement on 400kV OHL

The Romanian power grid was developed in the 60 and 70 and for that reason some major maintenance works should be done from time to time on the OHL. The mechanical condition of the lines has to be improved by replacing the tower anchors. One of the main concerns in the current strategy CNTEE TRANSELECTRICA S.A. is to ensure a reliable and economical operation of power grids. Higher requirements for safe operation of transmission lines, problems on their deenergising for repairs, led to the necessity of elaboration of new maintenance methods, mainly Live Maintenance technology. Using live maintenance for replacing the anchors some working conditions (weather conditions, risk analysis, distances) should be carefully considered. Working preparation is very important and following Romanian regulations, technical and safety procedures had to be designed and applied.

Live — Line surge arrester installing on a mountain section of the 400 kV Gutinas-Brasov o/h line (between towers 94–100)

The 400 kV Gutinas-Brasov o/h line is located in a mountain area with rocky soil. Because of the thick ice covering the conductors, during the winter times, causing the shieldwire breaking, the shieldwires were dismantled in the sections 94–100 and 130–145, long time ago. Without the shielding screen of the shieldwires those sections were left open to be struck by lightning. To reduce the lightning impact surge arresters were installed in two stages, the 2006 one, for the section 130–145 and the second one in 2013, for the section 94–100. Based on the first stage experience numerous improvements were applied for the second stage. No more lightning caused outages were recorded from the date of the first stage finalizing (2006–2016). Compared to the previous outage situation stating 4–10 outages per year, a very clear conclusion was drawn: a performant solution to protect the lines without shieldwires against the lightning strikes. Some improvements were proposed to the arrester manufacturer to increase the arrester component safety.

Electromagnetic field measurement inside live protective equipment on high voltage overhead lines

It has been settled by the international scientific community since the 90s that there are no direct biological effects, only physiological effects caused by densities of the currents higher than 10 mA/sqm induced into the human body. The maximal values recommended for the magnetic flux density in professional and residential exposure situations have been established by international and national organizations. The limits have been determined starting from the physiologic effect of the magnetic field based on a maximum density of current induced into the human body. Higher values of the limit are accepted in case of a short time professional exposure. Inside their special suites, the live workers are protected against the electric field, but not against the magnetic and torsion field. Some measurements where done on the usual towers in Romanian transmission grid, using also different types of electroconductive suites. Some protective measures against the field action should be proposed.

Live - line surge arrester installing on a mountain section of the 400 kV Gutinas- Brasov o/h line (between towers 94–100)

The line section of the existing 400 kV Gutinas- Brasov is located in a mountain area with rocky soil. Because of the thick ice covering the conductors during the winter times causing the shieldwire breaking the shieldwires had to be dismantled long time ago. Without the shielding screen of the shieldwires the line section was left open to be struck by lightning. To reduce the lightning impact the solution of arrester installing was selected. Two types of towers are to be analyzed to may find the best solutions to locate the arresters. Both the electrical and mechanical aspects were considered. The 400kV OHL Gutinas- Brasov being an important line it is very difficult to be deenergised. That was an important reason for which live working technologies were developed and applied for mounting the arresters.

Assessing the remaining life time of 220 kV and 400 kV OHTL and the required measures for the coordination of remaining life times of the various constructive elements of lines

The paper makes an analysis of the eighteen 220 and 400 kV overhead electric lines belonging to C.N. Transelectrica — Sibiu Branch (TSO) on the basis of a unitary methodology for assessing their technical state and taking into consideration the different types of expertise conducted until now, including the multispectral analysis from the helicopter of seven lines. Performance criteria for insulators, risk analysis of special route area and maintenance strategies to extend the normal life time have been established. Considering that different constructive elements of the line, located in a certain area, have different life times, concrete measures of lines alignment to obtain convergence of the partial remaining times have been established. Special attention was given to lines with major importance in the national electric system, proposing measures to increase their reliability based on detailed expertise methodology.